Well ever since MSE failed its AV certifcation, twice, I thought it was time to switch to a new AV. I have decided that AVG was the one I was going to go with, but I am curious of other opinions.
Avast is what I use. I decided to to branch out, and AVG is ok (using it on my gaming laptop), but I still prefer Avast Home Edition (used on main gaming rig)
I tried Comodo, but it installs a lot of extra junk. I haven't fully given Avira a chance, but I don't really like what I've used so far. If you're an FOSS advocate, I'd recommend ClamWin, but it requires a lot of user interaction as it doesn't come with a real-time scanner. There is one available but it scans EVERYTHING, it's called Clam Sentinal; I use the combination on my netbook.
The last intersting option that I haven't tried is Panda; it's cloud-based antivirus. If you're constantly connected to the internet and have limited hardware resources, Panda might be a good option.
Also use Avast, used to use AVG but it was to much of a resource hog. Haven't used it in years but it also liked to update and leave the Old version of the program installed after the up-date and that don't really seem like a problem till you look at it and realise your anti-virus is taking up 3gb of hard drive space. Thought of using Avira but I got Avast and I try not to use people I know as lab rats for Anti-virus test subjects so that will have to wait till I built my next computer. Most likely that problem doesn't exsist in AVG anymore since I quit using it back in 2008 or so and I'm sure enough people would have complained about it taking up most of their massive 16-32gb hard drives...
i use avast but i would also recomend NOD32, espicially if you want to throw some cash at it.
In related news its funny how AVG and Avast, both top quality virus spanking tools are made by Czech companies. Who would have thought that this small country is at the forefront of keeping computers healthy.